Processing of seafood including shell fish and crustaceans

ABSTRACT

A PACKAGE CONTAINING SEAFOOD PRODUCTS IN A PROCESSING LIQUID CONTAINING COPPER OR IRON IONS AND THE LIKE, INCLUDES A METALLIC CAN CONTAINING THE SEAFOOD COVERED WITHIN THE CAN WITH ALUMINUM FOIL AND THE LIKE, SAID PACKAGE HAVING   BEEN PROCESSED BY SUBJECTING THE CAN AND ITS CONTENTS TO ELEVATED TEMPERATURE.

D. 's. SPEARS May 29, 1973 PROCESSING OF SEAFOOD LNCLUDING SHELLFISH ANDCRUSTACEANS Filed June 11, 1970 lO-PLATED STEEL CAN [3-CRABMEAT METALLICMEMBER" lO-PLATE0 STEEL can IILALUMINUM FOIL msc INVENTOR.

DAN 5 pEARs A TTORNE Y5 United States Patent Ofice 3,736,153 PatentedMay 29, 1973 3,736,153 PROCESSING OF SEAFOOD INCLUDING SHELL- FISH ANDCRUSTACEANS Dan S. Spears, Columbia, S.C., assignor to The Blue ChannelCrp., Port Royal, S.C. Filed June 11, 1970, Ser. No. 45,443 Int. Cl.A2311 3/00 US. Cl. 99-188 1 Claim ABSTRACT OF THE DISCLOSURE A packagecontaining seafood products in a processing liquid containing copper oriron ions and the like, includes a metallic can containing the seafoodcovered within the can with aluminum foil and the like, said packagehaving been processed by subjecting the can and its contents to elevatedtemperature.

This invention relates to the controlling of objectionable discolorationin processed and packaged seafood products.

In the processing and packaging, namely canning, of seafood products,discoloration frequently results, and from the uninformed consumersviewpoint, this discoloration signifies an inferior product.

There are two primary causes of the blue and black color formed incanned seafood. First, the blood and flesh of the shellfish andcrustaceans, such as crabmeat, have a great abundance of heavy metalssuch as copper and iron. Also, there is inevitably some extraneousmatter introduced into the end product through the normal channels ofseafood processing. Some of these vectors carry the unwanted copper andiron. Examples of these vectors could be gills, viscera, shell, otherbody organs, occasionally seaweed, mud, etc. Also, these heavy metalscan be introduced through processing water, which is frequently drawnfrom wells, equipment, water pipes, and the like. The second source ofunwanted heavy metallic ions is the can used in packaging the finalproduct. This can is essentially a tin-plated steel can with variousgrades of enamel coating. During dating, sealing, processing, andsubsequent storage, this container may be the source of additionalunwanted ions. Of particular significance is the method of coding thedate on the can lid which almost invariably damages the enamel lining ofthe can. During the cooking process many cells of the meat rupture,exposing copper and iron to the free liquid in the can. These copper(Cu++) ions combine with sulfates present in the free liquid of the canto form blue copper sulfate. Also, iron in the meat and from the cancombine with sulfur present in the meat and water forming black ironsulfide. This problem was discussed in United States Pat. No. 2,669,520,issued to Carl R. Fellers on Feb. 16, 1954, and several remedies wereadvanced by him. The practice of this invention operates independentlyof Dr. Fellers development, although these two systems can be used tosupplement each other.

Accordingly, it is an important object of the present invention toimprove the appearance of canned seafood, especially crabmeat.

The construction designed to carry out the invention will be hereinafterdescribed, together with other features thereof.

The invention will be more readily understood from a reading of thefollowing specification and by reference to the accompanying drawingforming a part thereof, wherein an example of the invention is shown andwherein:

FIG. 1 is a schematic transverse sectional elevational view illustratinga preferred embodiment of the invention, and

FIG. 2 is a schematic transverse sectional elevational view illustratinga modified embodiment of the invention.

The practice of this invention contemplates an oxidation-reductionchemical reaction. Aluminum in its natural state with a valence of 0acts as a reducing agent and is oxidized by the copper (Cu++) ions.These copper ions accept electrons from the aluminum and actually formpure copper on the surface of the aluminum foil. This reaction can bepredicted from the use of a Latimer Oxidation Potential Chart, whichlists elements (ions) in their relative order of reducing power.Aluminum being more active than copper, displaces copper from its bluecomplexes CuSO forming white aluminum sulfate A1 (S00 and elementalcopper.

The half cell reactions are as follows:

A very similar reaction occurs in the case of iron. Aluminum possessinga greater reducing power as listed in 'Latimers Oxidation Potentialsdisplaces the iron from black iron sulfide.

Oxidation 2Al 66 2Al+++ Reduction 3Fe++ 66 3Fe This process was testedextensively in controlled experiments producing dramatic results. Theprocessed crab meat had a snow-white appearance.

There are several embodiments of the invention which will produce thedesired results and the particular modification employed will dependupon the cost factors for the particular product. One especiallydesirable embodiment includes a foil cup placed in the can which waslater folded over the top surrounding the crabmeat completely inaluminum foil. The can is sealed hermetically in the usual manner andretorted in the usual manner. In addition to protecting the delicateflavor and color of the seafood product, this foil liner presented aclean, wholesome appearance to the can and product. FIG. 1 illustratesthis preferred embodiment of the invention. A standard tin plate canwith enamel interior coating is illustrated at 10. A thin relativelyflat metallic member '11 is provided in the form of aluminum foil ofabout .003 thickness. The can is sealed by the usual lid 12. The flatmetallic member 11 is folded over the meat 13- as at Ma so as to be indirect contact therewith. The can is sealed as at 10a.

A package produced at minimal cost, with ease of packaging and producingdesired results included a foil disc of about .025 thickness over thetop of the meat which was folded inside a parchment cup. This can wassealed and retorted in the usual manner. FIG. 2 of the drawingillustrates this modification of the invention wherein like referencecharacters illustrate like parts with prime notations added. Theparch'ment cup is illustrated at 14 and is folded over the meat as at14a. The foil disc is designated at 11'.

Both modifications contained the usual additives, including a solublesequestering compound and a soluble buffering compound and the cans weresealed and retorted in the usual manner. The best results were achievedwhen the product 'was retorted with the top of the can and aluminum discin the up position. After storage for seven days the meat was found toremain white in appearance, while control samples containing the usualadditives including calcium disodium (EDTA), but without the aluminumfoil, exhibited undesirable discoloration. Crabmeat canned without anyadditives resulted in extensive discoloration on the surface andthroughout the meat.

Crabmeat (cocktail lump and jumbo lump) canned with the inclusion of theusual additives, such as soluble sequestering agents such as calciumdisodium (EDTA),

aluminum sulfate, and a soluble buffering compound, such as citric acidor phosphoric acid, did not produce desired results. Invariably theselumps of white meat formed bluegrey spots particularly, where they camein contact with the parchment which was against the inside of the can.Every test used this conventional method of color control which wasstandard operational procedure for packing crabmeat at the time. Thesuccessful method which is recommended here, uses aluminum foil discs tosupplement the action of the additives as described in Patv No.2,669,520. These additives include a small amount of solubleethylenediamine tetracetic acid or calcium disodium (EDTA) compound. Asmall amount of citric acid is preferably also used. The foil should beof sufficient thickness to facilitate handling.

Results using the foil were better at all points in time from one day totwo months. Observations were made after 24 hours. This was not enoughtime for either system to reach equilibrium. At least three days had tobe allowed under normal shelf storage to tell what the product was goingto look like after normal shelf storage. In a weeks time the blue-greyspots would invariably be removed from the surface of the meat touchingthe aluminum. Where the surfaces were in contact with the conventionalparchment, some blue-grey discoloration could be found. At least oneweek was normally allowed for storage before sample evaluation was made.Results after two months storage showed the foil producing excellentresults where controls still showed blue-grey spots. These sameconclusions can be drawn after seven months storage. When the foil wasplaced under the parchment cup improved results were achieved, but notas good as those achieved having foil in contact With product. Manyvariations of the above described embodiments, including placing foil atthe top and the bottom of the can, will produce desirable results. It,also, is believed that the invention would be applicable to otherseafood products including canned tuna, herring and the like.

The discoloration problem is aggravated by seasonal changes in thechemistry of the crab and becomes most pronounced during the late summermonths. While the discoloration could be controlled by the addition ofmore calcium disodium (EDTA) the amounts necessary would be beyondpermissible limits and would intrduce other undesirable factors. Theadditives used in practicing the invention should include solublecalcium disodium (EDTA) in desirable amounts and as permitted by theFood and Drug Administration under 275 parts per million. The additivesalso preferably include a soluble buffering compound.

The sealed cans of the invention are subjected to ele- .4 vatedtemperatures as, for example, in retorting, about 240 to 250 degreesFahrenheit, or pasteurizing, about to 200 degrees Fahrenheit. Whenpasteurization is used it is necessary to refrigerate the containers andcontents and the thin flat metallic member may be used alone withoutadditives. In any event the amount of calcium disodium (EDTA) and otheradditives may be reduced or even eliminated entirely by proper use ofthe foil.

While a preferred embodiment of the invention has been described usingspecific terms, such description is for illustrative purposes only, andit is to be understood that changes and variations may be made withoutdeparting from the spirit or scope of the following claims.

What is claimed is:

1. A package containing white lump crab meat in a processing liquidcontaining copper or iron ions including: a tin plated steel can havinga top for containing the crab meat; said can having a protectiveinterior enamel coating; a quantity of said crab meat and liquidsubstantially filling said can; a disc of aluminium foil contacting andsubstantially entirely covering said meat on one side thereof betweenthe crab meat and the top of the can; said crab meat and aluminum foildisc being substantially entirely surrounded by a parchment cup, saidaluminum foil being more active in order of reducing potential than themetal of the ions of the processing liquid; and calcium disodium EDTA, asoluble sequestering compound and a buffer as additives in theprocessing liquid; whereby discoloration of the white lump crab meat isavoided.

References Cited UNITED STATES PATENTS 1,679,543 8/1928 Rector 99-481 R1,958,765 5/1934 Perkins 99-181 R 2,299,090 10/ 1942 Hothersall 99181 R3,130,059 4/1964 Fried et al 99-181 R 2,669,520 2/1954 Fellers 99 -1881,592,726 7/1926 Dunbar 99188 2,027,270 1/1936 Fellers 99188 3,013,88412/1961 Fellers 99158 OTHER REFERENCES Food Engineering, October 1955,pp. 164-5. Food Engineering, April 1954, p. 144. Food Technology, May1965, pp. 102--106.

NORMAN YUDKOFF, Primary Examiner C. P. RIBANDO, Assistant Examiner "US.Cl. X.R.

